Free machining aluminum alloy with high melting point machining constituent

Abstract

A free machining aluminum alloy contains an effective amount of one or more high melting point constituents that provide enhanced machining capability. The high melting point constituents occupy from about 0.1 to about 3.0 volume percent of the aluminum alloy. The constituents can be any material that is essentially insoluble in the aluminum alloy matrix so as to form a discontinuity and one that will resist deformation during machining to enhance the formation of voids between the matrix and the free machining constituents. The constituents include elements, nitrides, oxides, borides, carbides, silicides, aluminides and combinations thereof that have a high melting point and high strength and low solubility in aluminum at the elevated temperature so that the constituents resist deformation during the machining operation. The free machining aluminum alloy can be formed as a workpiece and subjected to any machining operation.

What is claimed is:  
     
       1. In a free machining aluminum alloy article having at least one free machining constituent, the free machining constituent being present in the free machining aluminum alloy article in an amount to improve metal removal from the article during machining, the improvement comprising the free machining constituent being at least one high melting point material and the amount being between about 0.1 and 0.5% by volume of the free machining aluminum alloy. 
     
     
       2. The improvement of  claim 1 , wherein the high melting point material is one of an element and a compound. 
     
     
       3. The improvement of  claim 1 , wherein the high melting point material is a compound selected from the group consisting of a carbide, a nitride, a boride, a suicide, an oxide, and aluminide or a combination thereof. 
     
     
       4. The improvement of  claim 1 , wherein the high melting point material is one of: a) an oxide selected from the group consisting of aluminum, silicon oxide, titanium oxide, beryllium oxide, chromium oxide, thallium oxide, zirconium oxide, a rare earth oxide, magnesium oxide, iron oxide, nickel oxide, tantalum oxide, tungsten oxide, vanadium oxide, and combinations thereof; b) a carbide selected from the group consisting of titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, niobium carbide, tantalum carbide, chromium carbide, molybdenum carbide, tungsten carbide, iron carbide, silicon carbide, boron carbide and combinations thereof; c) a nitride selected from the group consisting of titanium nitride, zirconium nitride, hafnium nitride, vanadium nitride, tantalum nitride, niobium nitride, chromium nitride, iron nitride, silicon nitride, boron nitride, and combinations thereof; d) a boride selected from the group consisting of titanium boride, zirconium boride, hafnium boride, vanadium boride, niobium boride, tantalum boride, chromium boride, molybdenum boride, tungsten boride, and combinations thereof; and e) a silicide selected from the group consisting of titanium silicide, vanadium silicide, niobium silicide, tantalum silicide, chromium silicide, molybdenum silicide, tungsten boride, and combinations thereof. 
     
     
       5. The improvement of  claim 3 , wherein the compound is an aluminide. 
     
     
       6. The improvement of  claim 2 , wherein the material is an element selected from the group consisting of carbon, boron, tungsten, cobalt, tantalum, molybdenum, and the combination thereof. 
     
     
       7. The improvement of  claim 1 , wherein the aluminum alloy is selected from the group consisting of AA1000, AA2000, AA3000, AA5000, AA6000, and AA7000 series alloys. 
     
     
       8. The improvement of  claim 3 , wherein the aluminum alloy is one of an AA2000 and AA6000 series alloy. 
     
     
       9. The improvement of  claim 2 , wherein the material is an element selected from the group consisting of tungsten, cobalt, tantalum, molybdenum, and the combination thereof. 
     
     
       10. The improvement of  claim 1 , wherein the article is one of a forging, a rolling, and an extrusion.